JP2019002068A - Powder mixture for powder metallurgy and manufacturing method therefor - Google Patents
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- 239000000843 powder Substances 0.000 title claims abstract description 197
- 239000000203 mixture Substances 0.000 title claims abstract description 47
- 238000004663 powder metallurgy Methods 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 90
- 239000011230 binding agent Substances 0.000 claims abstract description 88
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 85
- 239000002994 raw material Substances 0.000 claims abstract description 79
- 229910052742 iron Inorganic materials 0.000 claims abstract description 40
- 239000002245 particle Substances 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims description 35
- 239000000463 material Substances 0.000 claims description 16
- 238000002844 melting Methods 0.000 claims description 14
- 230000008018 melting Effects 0.000 claims description 14
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 10
- 229930195729 fatty acid Natural products 0.000 claims description 10
- 239000000194 fatty acid Substances 0.000 claims description 10
- 150000004665 fatty acids Chemical class 0.000 claims description 10
- 239000011347 resin Substances 0.000 claims description 8
- 229920005989 resin Polymers 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 239000004952 Polyamide Substances 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 5
- 229920002647 polyamide Polymers 0.000 claims description 5
- 229920000573 polyethylene Polymers 0.000 claims description 5
- -1 polyethylenes Polymers 0.000 claims description 5
- 229920002635 polyurethane Polymers 0.000 claims description 5
- 239000004814 polyurethane Substances 0.000 claims description 5
- 238000000465 moulding Methods 0.000 abstract description 19
- 239000000428 dust Substances 0.000 abstract 1
- 239000000314 lubricant Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 5
- 229910002804 graphite Inorganic materials 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000011812 mixed powder Substances 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 238000005255 carburizing Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000000344 soap Substances 0.000 description 2
- 235000008708 Morus alba Nutrition 0.000 description 1
- 240000000249 Morus alba Species 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 description 1
- RKISUIUJZGSLEV-UHFFFAOYSA-N n-[2-(octadecanoylamino)ethyl]octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(=O)NCCNC(=O)CCCCCCCCCCCCCCCCC RKISUIUJZGSLEV-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/09—Mixtures of metallic powders
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/102—Metallic powder coated with organic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/108—Mixtures obtained by warm mixing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/16—Metallic particles coated with a non-metal
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/10—Metal compounds
- C08K3/11—Compounds containing metals of Groups 4 to 10 or of Groups 14 to 16 of the Periodic Table
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/35—Iron
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2302/00—Metal Compound, non-Metallic compound or non-metal composition of the powder or its coating
- B22F2302/40—Carbon, graphite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/005—Additives being defined by their particle size in general
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
本発明は、粉末冶金用粉末混合物に関し、特に、成形時に少ない力で金型から抜出すことができ、型かじりが抑制された粉末冶金用粉末混合物に関する。また本発明は、前記粉末冶金用粉末混合物の製造方法に関する。 The present invention relates to a powder mixture for powder metallurgy, and more particularly, to a powder mixture for powder metallurgy that can be extracted from a mold with a small force during molding, and mold galling is suppressed. The present invention also relates to a method for producing the powder mixture for powder metallurgy.
粉末冶金においては、鉄基粉末を主成分とする原料粉末を、金型を用いて成形して成形品（圧粉体）とし、前記成形品を焼結することによって焼結部品が製造される。そして、前記成型の際の成形性を良好にすることを目的として、前記原料粉末に潤滑剤を添加することや、前記成型に用いる金型の表面に潤滑剤を付着させておくことが、一般的に行われている。潤滑剤を使用しないと、原料粉末に含まれる鉄基粉末と金型とが直接接触するため、摩擦力が大きくなる。そしてその結果、成形時に目的とする圧粉密度にまで圧縮することができなかったり、成形後に成形品を金型から抜き出すときに大きな力を要したりするといった問題が生じる。 In powder metallurgy, a raw material powder composed mainly of iron-based powder is molded using a mold to form a molded product (compact), and the molded product is sintered to produce a sintered part. . And, for the purpose of improving the moldability at the time of molding, it is common to add a lubricant to the raw material powder or to attach a lubricant to the surface of the mold used for the molding. Has been done. Without the use of a lubricant, the iron-based powder contained in the raw material powder and the mold are in direct contact with each other, resulting in an increased frictional force. As a result, there arises a problem that it cannot be compressed to a desired green density at the time of molding or a large force is required when the molded product is extracted from the mold after molding.
このような理由から、圧粉成形に際して、様々な潤滑剤が用いられている。前記潤滑剤としては、例えば、ステアリン酸リチウム、ステアリン酸亜鉛などの金属石鹸、あるいはエチレンビスステアロアミドなどのアミド系潤滑剤が使用されている。 For these reasons, various lubricants are used in compacting. As the lubricant, for example, a metal soap such as lithium stearate or zinc stearate, or an amide lubricant such as ethylene bisstearamide is used.
また、特許文献１では、潤滑性向上のために黒鉛粉を用いることが提案されている。鉄基粉末の表面に黒鉛を被覆することにより、該鉄基粉末表面の潤滑性が向上する。また、黒鉛が介在することによって鉄基粉末と金型との直接接触が回避されるため、型かじりが防止される。 In Patent Document 1, it is proposed to use graphite powder to improve lubricity. By covering the surface of the iron-based powder with graphite, the lubricity of the iron-based powder surface is improved. In addition, the presence of graphite prevents direct contact between the iron-based powder and the mold, thereby preventing mold galling.
特許文献１で提案されているように、黒鉛粉が被覆された鉄基粉末を用いることによって、成形時の摩擦を低減し、金型からの抜出し力を低減することができる。しかし、特許文献１の粉末混合物には以下のような問題があることが分かった。 As proposed in Patent Document 1, by using an iron-based powder coated with graphite powder, it is possible to reduce the friction during molding and to reduce the extraction force from the mold. However, it was found that the powder mixture of Patent Document 1 has the following problems.
特許文献１では、黒鉛およびバインダを水または有機溶媒に分散した分散液を使用して、鉄基粉末の表面に黒鉛粉を被覆しているため、液体状の原料を取り扱うことができる製造設備が必要となる。特に、使用済みの溶媒を回収し、処理するための装置を設ける必要がある。 In Patent Document 1, since the surface of the iron-based powder is coated with graphite powder using a dispersion in which graphite and a binder are dispersed in water or an organic solvent, a manufacturing facility capable of handling liquid raw materials is provided. Necessary. In particular, it is necessary to provide an apparatus for collecting and processing the used solvent.
また、特許文献１では鉄基粉末に黒鉛粉を付着させるためにバインダが使用されているが、上記方法で得られる粉末混合物を調査した結果、鉄基粉末に付着した黒鉛粉の表面にもバインダが存在していることが分かった。粉末の表面にバインダが存在する結果、粉末混合物の流動性を十分に向上させることができない。 Further, in Patent Document 1, a binder is used to adhere the graphite powder to the iron-based powder, but as a result of investigating the powder mixture obtained by the above method, the binder is also applied to the surface of the graphite powder adhered to the iron-based powder. Was found to exist. As a result of the presence of the binder on the surface of the powder, the fluidity of the powder mixture cannot be sufficiently improved.
本発明は、上記実状に鑑みてなされたものであり、流動性に極めて優れ、少ない力で圧粉成形金型から抜出すことができ、成形時の型かじりが抑制された粉末冶金用粉末混合物を提供することを目的とする。また本発明は、溶媒を使用することなく、前記粉末冶金用粉末混合物を製造する方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, and is a powder mixture for powder metallurgy that is extremely excellent in fluidity, can be pulled out from a compacting mold with a small force, and suppresses mold galling during molding. The purpose is to provide. Another object of the present invention is to provide a method for producing the powder mixture for powder metallurgy without using a solvent.
本発明者らは、上記の課題を解決するため鋭意研究を行った結果、以下の知見を得た。 As a result of intensive studies to solve the above problems, the present inventors have obtained the following knowledge.
（１）原料粉末、黒鉛粉、およびバインダを同時に混合すると、黒鉛粉の表面にもバインダが被覆されてしまい、原料粉末の最表面に均一に黒鉛を被覆することができない。 (1) When the raw material powder, the graphite powder, and the binder are mixed at the same time, the binder is also coated on the surface of the graphite powder, and the outermost surface of the raw material powder cannot be uniformly coated with graphite.
（２）原料粉末の表面にバインダを被覆した後、微細な黒鉛粉を被覆することにより、黒鉛粉の表面がバインダで被覆されてしまうことを防止できる。そしてその結果、流動性に極めて優れ、成形時に少ない力で金型から抜出すことができ、型かじりが抑制された粉末冶金用粉末混合物を得ることができる。 (2) After coating the surface of the raw material powder with a binder, the surface of the graphite powder can be prevented from being coated with the binder by coating with fine graphite powder. As a result, it is possible to obtain a powder mixture for powder metallurgy that is extremely excellent in fluidity, can be extracted from the mold with a small force during molding, and mold galling is suppressed.
本発明は、上記知見に立脚するものであり、その要旨構成は次のとおりである。 The present invention is based on the above findings, and the gist of the present invention is as follows.
１．原料粉末と、バインダと、黒鉛粉とを含む粉末冶金用粉末混合物であって、
前記原料粉末が、該原料粉末の９０質量％以上の鉄基粉末を含有し、
前記黒鉛粉の平均粒径が５μｍ未満であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記バインダの質量（ｍb）の比率［ｍb／（ｍr＋ｍg）×１００］が、０．１０〜０．８０質量％であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記黒鉛粉の質量（ｍg）の比率［ｍg／（ｍr＋ｍg）×１００］が、０．６〜１．０質量％であり、
前記原料粉末の表面が、前記バインダの少なくとも一部で被覆されており、
前記原料粉末の表面に被覆された前記バインダの表面が、前記黒鉛粉の少なくとも一部で被覆されている、粉末冶金用粉末混合物。
1. A powder mixture for powder metallurgy containing raw material powder, a binder, and graphite powder,
The raw material powder contains 90% by mass or more of iron-based powder of the raw material powder,
The average particle size of the graphite powder is less than 5 μm;
The ratio [m b / (m r + m g ) × 100] of the binder mass (m b ) to the sum of the mass of the raw material powder (m r ) and the mass of the graphite powder (m g ) is 0.10. ~ 0.80 mass%,
The ratio [ mg / (m r + mg ) × 100] of the mass ( mg ) of the graphite powder to the total of the mass (m r ) of the raw material powder and the mass ( mg ) of the graphite powder is 0. 6-1.0% by mass,
The surface of the raw material powder is coated with at least a part of the binder,
A powder mixture for powder metallurgy, wherein the surface of the binder coated on the surface of the raw material powder is coated with at least a part of the graphite powder.
２．前記バインダが、脂肪酸アミド、共重合ポリアミド、ポリウレタン、およびポリエチレンからなる群より選択される１または２以上の樹脂である、上記１の粉末冶金用粉末混合物。 2. The powder mixture for powder metallurgy according to 1 above, wherein the binder is one or more resins selected from the group consisting of fatty acid amides, copolymerized polyamides, polyurethanes, and polyethylenes.
３．前記原料粉末が、合金用粉末および切削性改善材粉からなる群より選択される１または２以上の副原料を含有する、上記１または２に記載の粉末冶金用粉末混合物の製造方法。 3. 3. The method for producing a powder mixture for powder metallurgy according to 1 or 2 above, wherein the raw material powder contains one or more auxiliary raw materials selected from the group consisting of an alloy powder and a machinability improving material powder.
４．原料粉末とバインダとを、前記バインダの融点以上の温度で混合してバインダ被覆粉末とする第１混合工程と、
前記バインダ被覆粉末と平均粒径が５μｍ未満の黒鉛粉とを、前記バインダの融点以上の温度で混合して粉末冶金用粉末混合物とする第２混合工程とを有し、
前記原料粉末が、該原料粉末の９０質量％以上の鉄基粉末を含有し、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記バインダの質量（ｍb）の比率［ｍb／（ｍr＋ｍg）×１００］が、０．１０〜０．８０質量％であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記黒鉛粉の質量（ｍg）の比率［ｍg／（ｍr＋ｍg）×１００］が、０．６〜１．０質量％である、
粉末冶金用粉末混合物の製造方法。
4). A first mixing step of mixing the raw material powder and the binder at a temperature equal to or higher than the melting point of the binder to form a binder-coated powder;
A second mixing step of mixing the binder-coated powder and graphite powder having an average particle size of less than 5 μm at a temperature equal to or higher than the melting point of the binder to obtain a powder mixture for powder metallurgy,
The raw material powder contains 90% by mass or more of iron-based powder of the raw material powder,
The ratio [m b / (m r + m g ) × 100] of the binder mass (m b ) to the sum of the mass of the raw material powder (m r ) and the mass of the graphite powder (m g ) is 0.10. ~ 0.80 mass%,
The ratio [ mg / (m r + mg ) × 100] of the mass ( mg ) of the graphite powder to the total of the mass (m r ) of the raw material powder and the mass ( mg ) of the graphite powder is 0. 6-1.0% by mass,
A method for producing a powder mixture for powder metallurgy.
５．前記バインダが、脂肪酸アミド、共重合ポリアミド、ポリウレタン、およびポリエチレンからなる群より選択される１または２以上の樹脂である、上記４の粉末冶金用粉末混合物の製造方法。 5. 4. The method for producing a powder mixture for powder metallurgy according to 4 above, wherein the binder is one or more resins selected from the group consisting of fatty acid amide, copolymerized polyamide, polyurethane, and polyethylene.
６．前記原料粉末が、合金用粉末および切削性改善材粉からなる群より選択される１または２以上の副原料を含有する、上記４または５に記載の粉末冶金用粉末混合物の製造方法。 6). 6. The method for producing a powder mixture for powder metallurgy according to 4 or 5 above, wherein the raw material powder contains one or more auxiliary raw materials selected from the group consisting of alloy powder and machinability improving material powder.
本発明の粉末冶金用粉末混合物は、極めて優れた流動性を有している。そのため、成形時に少ない力で金型から抜出すことができるとともに、型かじりを生ずることなく連続成形を行うことができる。したがって、成形品の歩留まりが向上し、高い生産性を実現することができる。また、本発明の製造方法によれば、溶媒を用いることなく前記粉末冶金用粉末混合物を製造することができる。 The powder mixture for powder metallurgy of the present invention has extremely excellent fluidity. Therefore, it can be extracted from the mold with a small force during molding, and continuous molding can be performed without causing mold galling. Therefore, the yield of molded products can be improved and high productivity can be realized. Further, according to the production method of the present invention, the powder mixture for powder metallurgy can be produced without using a solvent.
以下、本発明を具体的に説明する。 Hereinafter, the present invention will be specifically described.
本発明の粉末冶金用粉末混合物は、原料粉末と、バインダと、黒鉛粉とを必須成分として含む。以下、前記各成分について説明する。 The powder mixture for powder metallurgy according to the present invention includes raw material powder, a binder, and graphite powder as essential components. Hereinafter, each component will be described.
［原料粉末］
上記原料粉末としては、鉄基粉末を含有する粉末を使用する。原料粉末中における鉄基粉末の比率は、９０質量％以上であればよいが、９５質量％以上とすることがより好ましい。一方、原料粉末中における鉄基粉末の比率の上限は特に限定されず、１００質量％とすることもできる。すなわち、前記原料粉末は、鉄基粉末のみからなるものであってもよい。しかし、最終的に得られる焼結体に様々な特性を付与するという観点からは、鉄基粉末と後述する副原料とからなる混合粉末を前記原料粉末として用いることが好ましい。
[Raw material powder]
As the raw material powder, a powder containing iron-based powder is used. The ratio of the iron-based powder in the raw material powder may be 90% by mass or more, but more preferably 95% by mass or more. On the other hand, the upper limit of the ratio of the iron-based powder in the raw material powder is not particularly limited, and may be 100% by mass. That is, the raw material powder may be composed only of iron-based powder. However, from the viewpoint of imparting various properties to the finally obtained sintered body, it is preferable to use a mixed powder composed of an iron-based powder and an auxiliary material described later as the raw material powder.
［鉄基粉末］
上記鉄基粉末としては、特に限定されることなく、任意のものを用いることができる。前記鉄基粉末の例としては、鉄粉（いわゆる純鉄粉）や合金鋼粉が挙げられる。前記合金鋼粉としては、合金元素を溶製時に予め合金化した予合金鋼粉（完全合金化鋼粉）、鉄粉に合金元素を部分拡散させて合金化した部分拡散合金化鋼粉、予合金化鋼粉にさらに合金元素を部分拡散させたハイブリッド鋼粉など、任意のものを用いることができる。なお、ここで「鉄基粉末」とは、Ｆｅ含有量が５０質量％以上である金属粉末を指し、「鉄粉」とは、Ｆｅおよび不可避不純物からなる粉末を指すものとする。
[Iron-based powder]
Any iron-based powder can be used without any particular limitation. Examples of the iron-based powder include iron powder (so-called pure iron powder) and alloy steel powder. Examples of the alloy steel powder include prealloyed steel powder (alloyed steel powder) prealloyed when the alloying element is melted, partially diffused alloyed steel powder that is alloyed by partially diffusing the alloying element in iron powder, Arbitrary things, such as a hybrid steel powder which further diffused the alloying element further to the alloyed steel powder, can be used. Here, “iron-based powder” refers to a metal powder having an Fe content of 50 mass% or more, and “iron powder” refers to a powder composed of Fe and inevitable impurities.
前記鉄基粉末の製造方法についても限定されず、任意の方法で製造された鉄基粉末を用いることができる。好適に使用できる鉄基粉末の例としては、アトマイズ法によって製造されるアトマイズ鉄基粉末（atomized iron-based powder）や、還元法によって製造される還元鉄基粉末（reduced iron-based powder）などが挙げられる。 The method for producing the iron-based powder is not limited, and an iron-based powder produced by any method can be used. Examples of iron-based powders that can be suitably used include atomized iron-based powders produced by the atomizing method and reduced iron-based powders produced by the reducing method. Can be mentioned.
前記鉄基粉末の平均粒径は、特に限定されないが、７０〜１００μｍとすることが好ましい。なお、鉄基粉末の粒径は、特に断りがない限り、ＪＩＳ Ｚ ２５１０：２００４に準拠した乾式ふるい分けによる測定値とする。 The average particle size of the iron-based powder is not particularly limited, but is preferably 70 to 100 μm. The particle size of the iron-based powder is a measured value by dry sieving based on JIS Z 2510: 2004 unless otherwise specified.
［副原料］
上記副原料としては、特に限定されることなく、粉末冶金において副原料として一般的に用いられるものなど任意のものを用いることができる。前記副原料としては、合金用粉末および切削性改善材粉からなる群より選択される１または２以上を用いることが好ましい。前記合金用粉末としては、一般的には金属粉末を用いることができる。前記金属粉末としては、例えば、Ｃｕ粉、Ｎｉ粉、およびＭｏ粉からなる群より選択される１または２以上を用いることが好ましい。また、前記切削性改善材粉としては、例えば、ＭｎＳなどが挙げられる。原料粉末における前記副原料の比率は、１０質量％以下とする。
[Sub raw materials]
The auxiliary material is not particularly limited, and any material such as those generally used as auxiliary materials in powder metallurgy can be used. As said auxiliary material, it is preferable to use 1 or 2 or more selected from the group which consists of powder for alloys and machinability improvement material powder. In general, a metal powder can be used as the alloy powder. As said metal powder, it is preferable to use 1 or 2 or more selected from the group which consists of Cu powder, Ni powder, and Mo powder, for example. Examples of the machinability improving material powder include MnS. The ratio of the auxiliary material in the raw material powder is 10% by mass or less.
［バインダ］
前記原料粉末の表面は、バインダの少なくとも一部で被覆される。前記バインダとしては、原料粉末の表面に黒鉛粉を付着させることができるものであれば、任意のものを用いることができる。例えば、脂肪酸モノアミドや脂肪酸ビスアミドなどの脂肪酸アミド、有機樹脂からなる群より選択される１または２以上を用いることができる。中でも、有機樹脂を用いることが好ましく、共重合ポリアミド、ポリウレタン、およびポリエチレンからなる群より選択される１または２以上の樹脂を用いることがより好ましい。
[Binder]
The surface of the raw material powder is coated with at least a part of a binder. Any binder can be used as long as it can attach graphite powder to the surface of the raw material powder. For example, one or more selected from the group consisting of fatty acid amides such as fatty acid monoamides and fatty acid bisamides, and organic resins can be used. Among these, it is preferable to use an organic resin, and it is more preferable to use one or more resins selected from the group consisting of copolymerized polyamide, polyurethane, and polyethylene.
バインダの添加量：０．１０〜０．８０質量％
前記バインダの添加量が０．１０質量％未満であると、原料粉末の最表面をバインダで十分に被覆することができない。そのため、バインダの添加量を０．１０質量％以上とする。一方、バインダの添加量が０．８０質量％を超えると バインダが黒鉛粉の表面も被覆してしまい、流動性が低下する。そのため、バインダの添加量を０．８０質量％以下とする。なお、ここでバインダの添加量は、原料粉末の質量（ｍr）と黒鉛粉の質量（ｍg）の合計に対する前記バインダの質量（ｍb）の比率［ｍb／（ｍr＋ｍg）×１００］と定義する。言い換えると、原料粉末と黒鉛粉の合計質量を１００質量部としたときの前記バインダの質量を０．１０〜０．８０質量部とする。
Addition amount of binder: 0.10 to 0.80 mass%
When the added amount of the binder is less than 0.10% by mass, the outermost surface of the raw material powder cannot be sufficiently covered with the binder. Therefore, the additive amount of the binder is set to 0.10% by mass or more. On the other hand, when the added amount of the binder exceeds 0.80% by mass, the binder also covers the surface of the graphite powder, and the fluidity is lowered. Therefore, the additive amount of the binder is set to 0.80% by mass or less. Here, the addition amount of the binder is the ratio of the mass (m b ) of the binder to the total mass (m r ) of the raw material powder and the mass ( mg ) of the graphite powder [m b / (m r + m g ). × 100]. In other words, the binder has a mass of 0.10 to 0.80 parts by mass when the total mass of the raw material powder and the graphite powder is 100 parts by mass.
前記バインダは、粉末状であることが好ましい。前記バインダの平均粒径が５μｍ未満であると、当該粒径まで粉砕するためのコストが増大し、原料費が高くなってしまう。そのため、バインダの平均粒径は５μｍ以上とすることが好ましい。一方、バインダの平均粒径が１００μｍを超える場合、原料粉末と均一に混合するために要する時間が増大し、生産性が低下する。そのため、バインダの平均粒径は１００μｍ以下とすることが好ましい。 The binder is preferably in the form of powder. When the average particle size of the binder is less than 5 μm, the cost for pulverizing to the particle size increases and the raw material cost increases. Therefore, the average particle diameter of the binder is preferably 5 μm or more. On the other hand, when the average particle size of the binder exceeds 100 μm, the time required for uniform mixing with the raw material powder increases, and the productivity decreases. Therefore, the average particle size of the binder is preferably 100 μm or less.
前記バインダの融点が６０℃未満であると、気温が高くなる夏場などに粉末混合物の流動性が低下してしまう。そのため、バインダの融点は６０℃以上であることが好ましい。一方、バインダの融点が１６０℃を越える場合、バインダの融点以上に加熱するために必要な時間やエネルギーが増大し、生産性が低下する。そのため、バインダの融点は１６０℃以下であることが好ましい。 If the melting point of the binder is less than 60 ° C., the fluidity of the powder mixture is lowered in summer when the temperature is high. Therefore, the melting point of the binder is preferably 60 ° C. or higher. On the other hand, when the melting point of the binder exceeds 160 ° C., the time and energy required for heating to the melting point or higher of the binder increase, and the productivity decreases. Therefore, the melting point of the binder is preferably 160 ° C. or lower.
［黒鉛粉］
前記原料粉末の表面に被覆された前記バインダの表面は、黒鉛粉の少なくとも一部で被覆される。言い換えると、原料粉末の表面には、バインダを介して黒鉛粉が被覆される。バインダを介して鉄基粉末の表面を黒鉛粉で被覆することによって、鉄基粉末表面の潤滑性が向上する。また、黒鉛粉が介在することによって、鉄基粉末と金型との直接接触が回避されるため、金型表面に鉄基粉末が付着、堆積することがなく、その結果、型かじりが起き難くなる。
[Graphite powder]
The surface of the binder coated on the surface of the raw material powder is coated with at least a part of graphite powder. In other words, the surface of the raw material powder is coated with graphite powder through the binder. By covering the surface of the iron-based powder with graphite powder via a binder, the lubricity of the iron-based powder surface is improved. In addition, since the graphite powder intervenes, direct contact between the iron-based powder and the mold is avoided, so that the iron-based powder does not adhere to and accumulate on the mold surface, and as a result, mold galling is unlikely to occur. Become.
黒鉛粉の平均粒径：５μｍ未満
一般的に粉末冶金で用いられる黒鉛粉の粒径は５〜２０μｍ程度である。一方、鉄基粉末は、一般的に、平均粒径が７０〜８０μｍ程度、最大で２５０μｍ程度である。黒鉛粉と鉄基粉末の粒径がこのような関係にある場合、黒鉛粉を鉄基粉末の表面に均一に被覆することが難しい。本発明では、鉄基粉末を含む原料粉末の表面に黒鉛粉を均一に被覆するために、黒鉛粉の平均粒径を５μｍ未満とする。一方、黒鉛粉の平均粒径の下限は特に限定されないが、過度に粒径を小さくすると、粉砕に必要なエネルギーが増大し、経済的に不利になる。そのため、黒鉛粉の平均粒径は１００ｎｍ以上とすることが好ましい。
Average particle diameter of graphite powder: less than 5 μm Generally, the particle diameter of graphite powder used in powder metallurgy is about 5 to 20 μm. On the other hand, the iron-based powder generally has an average particle size of about 70 to 80 μm and a maximum of about 250 μm. When the particle sizes of the graphite powder and the iron-based powder have such a relationship, it is difficult to uniformly coat the graphite powder on the surface of the iron-based powder. In this invention, in order to coat | cover graphite powder uniformly on the surface of the raw material powder containing iron group powder, the average particle diameter of graphite powder shall be less than 5 micrometers. On the other hand, the lower limit of the average particle size of the graphite powder is not particularly limited. However, if the particle size is excessively reduced, energy required for pulverization increases, which is economically disadvantageous. Therefore, the average particle size of the graphite powder is preferably 100 nm or more.
黒鉛粉の添加量：０．６〜１．０質量％
黒鉛の添加量が０．６質量％未満であると、鉄基粉末の最表面を黒鉛粉で十分に被覆することができず、鉄基粉末の表面が露出する。そのため、黒鉛粉による被覆の効果を十分に得るためには、黒鉛粉の添加量を０．６質量％以上とする必要がある。一方、黒鉛粉は最終的に焼結時の浸炭に消費され、焼結体の強度などの特性を高めるが、黒鉛粉の添加量が１．０質量％を超えると、かえって焼結体の特性が低下する。そのため、黒鉛粉の添加量は１．０質量％以下とする。なお、ここで黒鉛粉の添加量は、原料粉末の質量（ｍr）と黒鉛粉の質量（ｍg）の合計に対する前記黒鉛粉の質量（ｍg）の比率［ｍg／（ｍr＋ｍg）×１００］と定義する。
Addition amount of graphite powder: 0.6 to 1.0 mass%
When the added amount of graphite is less than 0.6% by mass, the outermost surface of the iron-based powder cannot be sufficiently covered with the graphite powder, and the surface of the iron-based powder is exposed. Therefore, in order to sufficiently obtain the effect of coating with graphite powder, the amount of graphite powder added needs to be 0.6% by mass or more. On the other hand, graphite powder is finally consumed by carburizing during sintering, and enhances properties such as strength of the sintered body. However, if the added amount of graphite powder exceeds 1.0% by mass, the properties of the sintered body are increased. Decreases. Therefore, the addition amount of graphite powder shall be 1.0 mass% or less. Here, the addition amount of the graphite powder is the ratio of the mass of the graphite powder ( mg ) to the total of the mass of the raw material powder (m r ) and the mass of the graphite powder ( mg ) [ mg / (m r + m g ) × 100].
［製造方法］
次に、上記粉末冶金用粉末混合物の製造方法について説明する。本発明の一実施形態における製造方法は、原料粉末とバインダとを、前記バインダの融点以上の温度で混合してバインダ被覆粉末とする第１混合工程と、前記バインダ被覆粉末と平均粒径が５μｍ未満の黒鉛粉とを、前記バインダの融点以上の温度で混合して粉末冶金用粉末混合物とする第２混合工程とを有する。
[Production method]
Next, a method for producing the powder mixture for powder metallurgy will be described. The manufacturing method in one embodiment of the present invention includes a first mixing step in which raw material powder and a binder are mixed at a temperature equal to or higher than the melting point of the binder to form a binder-coated powder, and the binder-coated powder and the average particle size are 5 μm. Less graphite powder at a temperature equal to or higher than the melting point of the binder to form a powder mixture for powder metallurgy.
バインダと黒鉛粉とを予め混合してしまうと、バインダの粘度が増加し、その結果、原料粉末の表面に均一にバインダを被覆することが困難となる。そのため、黒鉛粉を被覆する工程に先立って、鉄基粉末の表面にバインダを被覆する工程を実施する。これにより、原料粉末の表面にバインダのみを均一に被覆することができる。上記観点からは、第１混合工程では原料粉末に対してバインダのみを添加混合することが好ましい。また、第２混合工程では、バインダが被覆された原料粉末（バインダ被覆粉末）に対して、さらにバインダを添加することなく、黒鉛粉のみを添加混合することが好ましい。 If the binder and graphite powder are mixed in advance, the viscosity of the binder increases, and as a result, it becomes difficult to uniformly coat the surface of the raw material powder. Therefore, prior to the step of coating the graphite powder, a step of coating the binder on the surface of the iron-based powder is performed. Thereby, only the binder can be uniformly coated on the surface of the raw material powder. From the above viewpoint, it is preferable to add and mix only the binder to the raw material powder in the first mixing step. In the second mixing step, it is preferable to add and mix only the graphite powder without adding a binder to the raw material powder (binder-coated powder) coated with the binder.
また、バインダと黒鉛粉を原料粉末の表面に同時に被覆すると、黒鉛粉の表面にもバインダが被覆されてしまうため、黒鉛粉による被覆の効果を十分に得ることができない。そこで、バインダを被覆した後に黒鉛粉を被覆することにより、黒鉛粉の表面がバインダで被覆されてしまうことを防止できる。言い換えると、本発明の方法で得られる粉末冶金用粉末混合物においては、原料粉末表面が、バインダを介して付着した黒鉛粉によって均一に被覆されている。また、原料粉末粒子表面にはバインダがほとんど露出しておらず、黒鉛粉が外側にあるため、流動性や金型成形時の抜出性に優れる。 In addition, if the surface of the raw material powder is coated with the binder and the graphite powder at the same time, the binder is also coated on the surface of the graphite powder, so that the effect of coating with the graphite powder cannot be sufficiently obtained. Therefore, by coating the graphite powder after coating the binder, it is possible to prevent the surface of the graphite powder from being coated with the binder. In other words, in the powder mixture for powder metallurgy obtained by the method of the present invention, the raw material powder surface is uniformly coated with the graphite powder adhered via the binder. Moreover, since the binder is hardly exposed on the surface of the raw material powder particles, and the graphite powder is on the outside, the fluidity and the pullability during molding are excellent.
第１混合工程および第２混合工程で用いる混合手段としては、特に制限はなく、各種公知の混合機など任意のものを使用できる。加熱が容易であるという観点からは、高速底部撹拌式混合機、傾斜回転パン型混合機、回転クワ型混合機、または円錐遊星スクリュー形混合機を用いることが好ましい。 There is no restriction | limiting in particular as a mixing means used at a 1st mixing process and a 2nd mixing process, Arbitrary things, such as various well-known mixers, can be used. From the viewpoint of easy heating, it is preferable to use a high-speed bottom stirring mixer, an inclined rotary pan mixer, a rotary mulberry mixer, or a conical planetary screw mixer.
前記第１混合工程および第２混合工程を実施する際の混合温度は、使用するバインダの融点（Ｔm）以上とする。なお、融点の異なる複数のバインダを併用する場合には、使用する複数のバインダの融点のうち最も高いものをＴmとして用いる。前記混合温度は、Ｔm＋２０℃以上とすることが好ましく、Ｔm＋５０℃以上とすることが好ましい。一方、前記混合温度の上限は特に限定されないが、混合温度を過度に高くすると生産効率が低下する、鉄基粉末が酸化するなどの弊害が生じるため、Ｔm＋１００℃以下とすることが好ましい。 The mixing temperature when carrying out the first mixing step and the second mixing step is set to be equal to or higher than the melting point (T m ) of the binder used. When a plurality of binders having different melting points are used in combination, the highest melting point of the plurality of binders used is used as Tm . The mixing temperature is preferably T m + 20 ° C. or higher, and preferably T m + 50 ° C. or higher. On the other hand, the upper limit of the mixing temperature is not particularly limited. However, if the mixing temperature is excessively high, production efficiency is lowered and iron-based powder is oxidized, so that T m + 100 ° C. or lower is preferable.
上記のようにして得られた粉末混合物は、粉末冶金による焼結体の製造に用いることができる。前記焼結体の製造方法は特に限定されず、任意の方法で製造することができるが、通常は、前記粉末冶金用粉末混合物を金型に充填し圧縮成形し、必要に応じてサイジングを行った後、焼結すればよい。前記圧縮成形は、一般的に室温から１８０℃の温度領域で行われるが、特に圧粉体の密度を高くする必要がある場合には、粉体および金型を共に予熱しておいて成形する温間成形を採用することもできる。得られた焼結体は、さらに必要に応じて浸炭焼入れ、光輝焼入れ、高周波焼入れなどの熱処理を施して、製品（機械部品等）とすることができる。 The powder mixture obtained as described above can be used for producing a sintered body by powder metallurgy. The method for producing the sintered body is not particularly limited, and can be produced by any method. Usually, the powder mixture for powder metallurgy is filled in a mold and compression-molded, and sizing is performed as necessary. And then sintering. The compression molding is generally performed in a temperature range from room temperature to 180 ° C. Especially when it is necessary to increase the density of the green compact, both the powder and the mold are preheated and molded. Warm forming can also be employed. The obtained sintered body can be further subjected to heat treatment such as carburizing quenching, bright quenching, and induction quenching as necessary to obtain a product (mechanical part or the like).
なお、本発明の粉末冶金用粉末混合物には、上記第２混合工程の後に、さらに任意に追加の副原料および潤滑剤の一方または両方を添加することもできる。前記追加の副原料としては、上述した原料粉末に含有させる副原料と同様のものを用いることができる。また、前記潤滑剤としては、有機樹脂ではない潤滑剤を用いることが好ましく、脂肪酸、脂肪酸アミド、脂肪酸ビスアミド、および金属石鹸からなる群より選択される１または２以上の潤滑剤を用いることがより好ましい。 In addition, to the powder mixture for powder metallurgy of the present invention, one or both of an additional auxiliary material and a lubricant can be optionally added after the second mixing step. As said additional auxiliary material, the thing similar to the auxiliary material contained in the raw material powder mentioned above can be used. Moreover, it is preferable to use a lubricant that is not an organic resin as the lubricant, and it is more preferable to use one or more lubricants selected from the group consisting of fatty acids, fatty acid amides, fatty acid bisamides, and metal soaps. preferable.
以下、実施例に基づいて本発明の構成および作用効果をより具体的に説明する。なお、本発明は下記の例に限定されるものではない。 Hereinafter, based on an Example, the structure and effect of this invention are demonstrated more concretely. In addition, this invention is not limited to the following example.
以下の手順で粉末冶金用粉末混合物を製造した。まず、原料粉末とバインダとを、高速底部撹拌式混合機で混合しながら所定の混合温度に加熱した（第１混合工程）。前記原料粉末としては、鉄基粉末としての鉄粉（ＪＦＥスチール社製アトマイズ鉄粉ＪＩＰ３０１Ａ）および副原料としてのＣｕ粉からなる原料粉末を用いた。使用したバインダの種類と、各成分の添加量、および混合温度を表１に示す。 A powder mixture for powder metallurgy was produced by the following procedure. First, the raw material powder and the binder were heated to a predetermined mixing temperature while mixing with a high-speed bottom stirring mixer (first mixing step). As said raw material powder, the raw material powder which consists of iron powder (Atomized iron powder JIP301A by JFE Steel Co., Ltd.) as iron-base powder, and Cu powder as an auxiliary material was used. Table 1 shows the type of binder used, the amount of each component added, and the mixing temperature.
次いで、前記高速底部撹拌式混合機中へ、さらに黒鉛粉を添加し、前記混合温度に加熱した状態で混合した（第２混合工程）。混合終了後、得られた粉末冶金用粉末混合物を混合機から排出した。前記黒鉛粉としては、表１に示した平均粒径を有する、市販の黒鉛粉を使用した。 Next, graphite powder was further added into the high-speed bottom stirring mixer, and the mixture was heated to the mixing temperature and mixed (second mixing step). After mixing, the obtained powder mixture for powder metallurgy was discharged from the mixer. As the graphite powder, commercially available graphite powder having the average particle size shown in Table 1 was used.
なお、比較のために、一部の比較例においては、前記第２混合工程において黒鉛粉を添加することに代えて、前記第１混合工程において黒鉛粉を添加した。また、一部の比較例（Ｎｏ．１７）では、上記第１混合工程および第２混合工程において加熱を行わず、室温で混合を行った。Ｎｏ．１７では、加熱せずに混合を行ったため、原料粉末の表面は、バインダおよび黒鉛粉で被覆された状態とならなかった。 For comparison, in some comparative examples, graphite powder was added in the first mixing step instead of adding graphite powder in the second mixing step. In some comparative examples (No. 17), heating was not performed in the first mixing step and the second mixing step, and mixing was performed at room temperature. No. In No. 17, since mixing was performed without heating, the surface of the raw material powder was not covered with the binder and the graphite powder.
次に、得られた粉末冶金用混合粉末のそれぞれについて、以下に述べる手順で流動度の測定および成型体の加圧成形を実施した。 Next, for each of the obtained mixed powders for powder metallurgy, the flow rate was measured and the molded body was pressure-molded by the procedure described below.
（流動度）
得られた粉末冶金用粉末混合物５０ｇを、オリフィス径：２．５ｍｍの容器に充填し、充填してから排出するまでの時間を測定して、流動度（単位：ｓ／５０ｇ）を求めた。なお、その他の測定条件は、ＪＩＳ Ｚ ２５０２：２０１２に準拠した。流動度は、金型充填時の混合粉の流動性を示す指標であり、流動度の値が小さいほど混合粉の流動性が優れていることを意味する。なお、一部の比較例では粉末冶金用粉末混合物が流れず、オリフィスから排出されなかった。
(Fluidity)
50 g of the obtained powder mixture for powder metallurgy was filled in a container having an orifice diameter of 2.5 mm, and the time from filling to discharging was measured to determine the fluidity (unit: s / 50 g). Other measurement conditions were based on JIS Z 2502: 2012. The fluidity is an index indicating the fluidity of the mixed powder at the time of mold filling, and the smaller the value of the fluidity, the better the fluidity of the mixed powder. In some comparative examples, the powder mixture for powder metallurgy did not flow and was not discharged from the orifice.
（加圧成形）
加圧成形では、上記粉末冶金用粉末混合物を、金型を用いて加圧成形し、径：１１．３ｍｍ、高さ：１１ｍｍの成形体を得た。前記加圧成形における成形圧力は６８６ＭＰａとした。前記成形体を金型から抜き出すときに必要な力（抜出力）と、得られた成形体の圧粉密度（成形体の平均）とを測定した。なお、一部の比較例では型かじりが発生して成形を行うことができなかった。
(Pressure molding)
In the pressure molding, the powder mixture for powder metallurgy was pressure molded using a mold to obtain a molded body having a diameter of 11.3 mm and a height of 11 mm. The molding pressure in the pressure molding was 686 MPa. The force (pulling output) required when the molded body was extracted from the mold and the green density (average of the molded body) of the obtained molded body were measured. In some comparative examples, galling occurred and molding could not be performed.
測定結果は、表１に示したとおりであった。この結果から分かるように、本発明の条件を満たす粉末冶金用粉末混合物は、流動性に極めて優れ、少ない力で圧粉成形金型から抜出すことができ、かつ成形時の型かじりも抑制されていた。 The measurement results were as shown in Table 1. As can be seen from this result, the powder mixture for powder metallurgy that satisfies the conditions of the present invention is extremely excellent in fluidity, can be pulled out from a compacting mold with a small force, and mold galling during molding is also suppressed. It was.
Claims (6)
前記原料粉末が、該原料粉末の９０質量％以上の鉄基粉末を含有し、
前記黒鉛粉の平均粒径が５μｍ未満であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記バインダの質量（ｍb）の比率［ｍb／（ｍr＋ｍg）×１００］が、０．１０〜０．８０質量％であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記黒鉛粉の質量（ｍg）の比率［ｍg／（ｍr＋ｍg）×１００］が、０．６〜１．０質量％であり、
前記原料粉末の表面が、前記バインダの少なくとも一部で被覆されており、
前記原料粉末の表面に被覆された前記バインダの表面が、前記黒鉛粉の少なくとも一部で被覆されている、粉末冶金用粉末混合物。 A powder mixture for powder metallurgy containing raw material powder, a binder, and graphite powder,
The raw material powder contains 90% by mass or more of iron-based powder of the raw material powder,
The average particle size of the graphite powder is less than 5 μm;
The ratio [m b / (m r + m g ) × 100] of the binder mass (m b ) to the sum of the mass of the raw material powder (m r ) and the mass of the graphite powder (m g ) is 0.10. ~ 0.80 mass%,
The ratio [ mg / (m r + mg ) × 100] of the mass ( mg ) of the graphite powder to the total of the mass (m r ) of the raw material powder and the mass ( mg ) of the graphite powder is 0. 6-1.0% by mass,
The surface of the raw material powder is coated with at least a part of the binder,
A powder mixture for powder metallurgy, wherein the surface of the binder coated on the surface of the raw material powder is coated with at least a part of the graphite powder.
前記バインダ被覆粉末と平均粒径が５μｍ未満の黒鉛粉とを、前記バインダの融点以上の温度で混合して粉末冶金用粉末混合物とする第２混合工程とを有し、
前記原料粉末が、該原料粉末の９０質量％以上の鉄基粉末を含有し、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記バインダの質量（ｍb）の比率［ｍb／（ｍr＋ｍg）×１００］が、０．１０〜０．８０質量％であり、
前記原料粉末の質量（ｍr）と前記黒鉛粉の質量（ｍg）の合計に対する前記黒鉛粉の質量（ｍg）の比率［ｍg／（ｍr＋ｍg）×１００］が、０．６〜１．０質量％である、
粉末冶金用粉末混合物の製造方法。 A first mixing step of mixing the raw material powder and the binder at a temperature equal to or higher than the melting point of the binder to form a binder-coated powder;
A second mixing step of mixing the binder-coated powder and graphite powder having an average particle size of less than 5 μm at a temperature equal to or higher than the melting point of the binder to obtain a powder mixture for powder metallurgy,
The raw material powder contains 90% by mass or more of iron-based powder of the raw material powder,
The ratio [m b / (m r + m g ) × 100] of the binder mass (m b ) to the sum of the mass of the raw material powder (m r ) and the mass of the graphite powder (m g ) is 0.10. ~ 0.80 mass%,
The ratio [ mg / (m r + mg ) × 100] of the mass ( mg ) of the graphite powder to the total of the mass (m r ) of the raw material powder and the mass ( mg ) of the graphite powder is 0. 6-1.0% by mass,
A method for producing a powder mixture for powder metallurgy.
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